It depends on so many things. If you are on time, if you have cleared customs, if you are allowed to walk off carrying your own luggage and if the train station is close to the port you may make it but I more than doubt it.
Just because it's due in at a certain time it usually means at least a 1/2 hour after that (or more) before you can start off-loading.
I sailed Splendour out of Venice a few years ago. My wife and I did early walk off; we rolled our bags off the ship; we were in parking lot at around 7:15. The ship actually was early into Venice. She docked at 5:15am.
Freedom of the Seas Dec 11
Allure of the Seas: Jan 11
Voyager of the Seas: May 09
Splendour of the Seas: May 07
Explorer of the Seas: Jan 04
Majesty of the Seas Jan 99